1. Field of the Invention
The present invention relates to a window system for displaying a single or a plurality of windows overlapping one another on a display screen for display of characters and/or graphics under control of a computer and more particularly, to a window display system for presenting overlapped windows in such a form that a user can comprehend intuitively the overlapped window structure in a user-friendly manner.
2. Description of the Related Art
With respect to a so-called multi-window system for displaying a plurality of windows overlapping one another, there have already been suggested many systems which include (1) a system for presenting the front/back relationship of the windows in a user-friendly manner and (2) a system for depicting the front/back relationship of the windows efficiently.
The present invention is directed to systems of the above type (1). With regard to this type of system, that is, a system for presenting a multiplicity of windows overlapped (or arranged in a Z (depth) direction of a two-dimensional display screen) in a user-friendly manner on the display screen; there have been proposed systems which follow.
Japanese Laid-open Patent Application No. 2-250113 describes a graphic display for presenting graphic elements on a display screen stereoscopically or three-dimensionally by applying shades and shadows to the elements. In this graphic display, since a window frame is also stereoscopically depicted, this makes a boundary with another window more clear and thus the front/back relationship between the windows can be presented in a user-friendly manner.
In the graphic display, further, by applying shades and shadows also to graphic elements within the window and depicting stereoscopically shades and shadows cast by the window itself on a deeper (more distant) window, stereoscopical or three-dimensional array information on the overall display screen can be visually presented in the easy-to-understand manner.
Japanese Laid-open Patent Application No. 1-261722 discloses a multi-window display control system which puts all active windows that are in front of (shallower than) a window now of interest in their non-display state. This multi-window display control system can display only the window now of interest without changing the front/back relationship between the windows. Further, since the window front/back relationship is not changed, this also reduces the possibility of causing the user to get confused by the window front/back relationship.
In this way, the prior art systems presenting the window front/back relationship in a user-friendly manner have in common in that the display screen is arranged to effectively present a three-dimensional array of windows or the like.
The foregoing prior art systems however have problems which follow.
The first problem in the prior art is that, since the outer frames of the windows are contrasting in order to clearly distinguish between the inside and outside of the windows, the window boundary areas represented by the frames may become unnoticeable or unremarkable in some situations. More specifically, though the outer frames of the windows are contrasting by broadening the window frames, presenting them in striking color or stereoscopically, this method leads to the fact that the visual impact of the outer frames of the windows depends on the display content within the window frames. More in detail, the window frames become relatively unremarkable (1) when the graphic images within the window frames have a color tone design more visually noticeable than that of the window frames or (2) when the interior graphic images include a color tone or design very similar to that of the window frames. In this connection, since the graphic images within the window frames can be freely chose by the user, the possibility that the window frames become relatively unnoticeable cannot entirely be avoided.
The second problem in the foregoing prior art systems is that, even if the window frames can be sufficiently distinct, the window front/back (depth) relationship is presented simply by not displaying the hidden window areas of the other windows, for which reason it is difficult to recognize the front/back relationships among a multiplicity of windows.
That is, in the prior art systems, (1) it inevitably becomes hard to recognize the window front/back relationship when the window frames are unnoticeable, and in a certain display screen, (2) the window front/back relationship must be perceived on the basis of the window or the displayed contents (such as figures) of the window frames (for example, perception is such that, although the window is hidden by another window, its window area will be regarded by the user as actually existing). Accordingly, as the windows are overlapped in a more complicated way, it becomes more difficult to recognize the window front/back relationship.
In view of the above problems in the prior art, it is therefore an object of the present invention to provide a 3-D model window display system which, taking an array of windows in their depth direction (Z direction) into consideration, provides a dynamic change to the display coordinates, display scale factor, etc. of each window in response to a movement of a virtual viewing point operated by a user on a real time basis, thereby to give an impression to the user of the windows overlapping in a three-dimensional space. This allows the user to perceive intuitively the boundary areas of the windows or positional relationships therebetween and can improve the ease of use of the window system.